H8SSLASH2224 datasheet(569/1071 Pages) RENESAS

569 / 1071 page

Section 14 IEBus™ Controller (IEB) [H8S/2258 Group]

Rev. 5.00 Aug 08, 2006 page 483 of 982

REJ09B0054-0500

14.1.1

IEBus Communications Protocol

The overview of the IEBus is described below.

• Communications method: Half duplex asynchronous communications

• Multi-master system

All units connected to the IEBus can transfer data to other units.

• Broadcast communications function (one-to-many communications)

 Group broadcast communications: Broadcast communications to group unit

 General broadcast communications: Broadcast communications to all units

• Mode is selectable (three modes with different transfer speeds).

Table 14.1 Mode Types

Mode

φφφφ = 12 MHz

φφφφ = 12.58 MHz

Maximum Number of

Transfer Bytes (byte/frame)

About 3.9 kbps

About 4.1 kbps

About 17 kbps

About 18 kbps

About 26 kbps

About 27 kbps

128

• Access control: CSMA/CD (Carrier Sense Multiple Access with Collision Detection)

Priority of bus mastership is as follows.

 Broadcast communications (one-to-many communications) have priority rather than

normal communications (one-to-one communications).

 Smaller master address has priority.

• Communications scale

 Number of units: Up to 50

 Cable length: Up to 150 m (when using a twisted pair cable)

Note: The communications scale of the actual system depends on the externally mounted IEBus

driver/receiver characteristics and the characteristics of the cable to be used.

(1) Determination of Bus Mastership (Arbitration)

A unit connected to the IEBus performs an operation for getting the bus to control other units. This

operation is called arbitration. In arbitration, when the multiple units start transfer simultaneously,

the bus mastership is given to one unit among them.

Only one unit can get bus mastership through arbitration, so the following priority for bus

mastership is defined.

H8S/2224 Scheda tecnica(PDF) 569 Page - Renesas Technology Corp

H8S/2224 Scheda tecnica(HTML) 569 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Scheda tecnica Scarica

Link URL